1. Field of the Invention
The present invention relates to a valve assembly which can be used to regulate fluid flow, particularly for use as a shut-off valve.
2. Related Art
In many conventional shut-off valves, a sealing member is rotated between an open and closed position, the sealing member completely blocking a fluid flow path in the closed position and the valve allowing fluid flow through a lumen extending through the shut-off valve in the open position. Typically, when the sealing member is in the open position, the lumen is aligned with the fluid flow and turning the valve by 90 degrees in either direction rotates the sealing member and turns the lumen perpendicular to the flow path, thereby shutting off fluid flow. To provide a sufficiently tight seal, particularly when the fluid is pressurized, the sealing member is typically constructed from elastomeric materials, such as rubber. One drawback of these conventional shut-off valves is that the seal typically degrades over time, eventually allowing fluid to leak when the valve is in the closed position.
The valve-seal may become compromised for a variety of reasons, including differences in tolerances of the sealing member and fluid conduit, parting lines, debris, and sealing defects due to the elastomer “taking a set.” Additionally, the force of the fluid upstream of the seal may compromise the effectiveness of the seal and may make movement of the sealing member between the open positions difficult. Often, in conventional sealing devices, when the sealing member is disposed in the open configuration over time, the force of the fluid may press the seal against the walls of the conduit causing the elastomeric seal to take a “set” and retain its shape in the open position, even when moved into the closed position. This retained shape or “set” reduces the effectiveness of the seal in the closed position, eventually allowing fluid to leak past the seal in the closed position.
It is an object of the present invention to provide an improved shut-off valve that alleviates one or more of the above drawbacks of conventional shut-off valves.